1. Field of the Invention
The present invention relates to a novel optical recording medium comprising an optical recording layer containing gelled polymer swollen by a solvent.
2. Related Background Art
Gels made from crosslinked polymer are classified into two groups; hydro-gel containing water as a liquid component, and organo-gel containing an organic solvent. Structural stability of gel is known to vary depending upon the structure of the crosslinked polymer itself and the intermolecular force between the crosslinked polymer and the liquid component. It has been also known that a gelled polymer swollen by a solvent exhibits phase separation by reversible phase transition depending on the surrounding conditions such as temperature, the composition of the solvent, pH, electric field, etc. Although the gelled polymer is subtransparent when swollen by a solvent, the gel polymer is deprived of the solvent by phase transition, and finally it reaches shrunk state through a white turbid stage.
Making use of phase transition of the gelled polymer, gels have been studied for new applications including various kinds of recording media, display device, switch element, transport medium for solvent, etc.
However, a gelled polymer which responds to light irradiation and which, as a result, undergoes phase transition had not been known.